南蒙古汗博格德地区石炭纪火山碎屑岩沉积学研究及其对古亚洲洋晚期演化的约束

中亚造山带是典型的显生宙增生造山带，石炭纪之前主要发育侧向增生作用，而石炭纪之后可能存在一定的垂向增生。因此，石炭纪是理解中亚造山带末期构造演化的关键时期。南蒙古拼合体系是中亚造山带晚古生代典型的增生造山区，发育大量的石炭纪岩浆岩和火山碎屑岩。尽管石炭纪岩浆岩取得了重要的研究成果，但关于南蒙古石炭纪弧的性质到底是洋内弧还是陆缘弧仍存在争议，导致对其精细的俯冲过程认识不清。南蒙古地区石炭纪火山岩以年轻物质加入为主，因此以近源物质为主的火山碎屑岩对不同来源的物质加入非常敏感。基于此，本项目针对南蒙古戈壁天山构造带汗博格德地区石炭纪火山碎屑岩展开综合的沉积学研究：在系统的沉积相和沉积环境研究的基础上，利用Nd同位素和锆石U-Pb年代学约束南蒙古戈壁天山构造带石炭纪弧的性质，通过锆石Hf-O同位素揭示石炭纪地壳改造和生长历史，以期为中亚造山带中段末期构造演化过程提供新的约束。

The Central Asian Orogenic Belt (CAOB) is a typical Phanerozoic accretionary orogenic belt. It has a main lateral accretion before the Carboniferous and then possibly add some vertical accretion since the Permian. Thus, the Carboniferous is very important time for the late-stage evolution of the CAOB. The southern Mongolia Collage System (MCS) is a critical region of late Paleozoic accretion and has abundant Carboniferous magmatic and volcanoclastic rocks. Although much progress has been achieved, the nature of the Carboniferous arc there is controversial and reasonably unclear on its tectonic evolution. The Carboniferous volcanic rocks has young composition (suggested by Hf and Nd isotopes from previous work) and thus the related volcanoclastic rocks are very sensitive to material from other provenance (especially old crust). Thus, a detailed sedimentary study on the Carboniferous volcanic rocks from the Khan-Bogd region, southern MCS will be carried out. First, the study on their sedimentary facies and sedimentary environment is essential and fundamental. Second, the nature of this southern MCS Carboniferous arc will be constrained by Nd isotope and zircon U-Pb geochronology. Third, the crust growth and reworking history will be revealed by zircon Hf-O isotope. Through this work, we will provide new constraints on the late-stage tectonic evolution of the CAOB.